no cucumbers on vine

Are the cucumber vines blooming yet? Most varieties must be pollinated before they will form fruit. (There are a few exceptions, called parthenocarpic, or seedless cucumbers.) The first blossoms that form on the vine are all male. Eventually most varieties begin to alternate male and female blossoms. Only the female blossoms can develop into fruit. You can tell the difference by looking at the base of the blossom. Male blossoms will have a thin stalk supporting them. Female blossoms will have a swollen stalk that resembles a miniature cucumber. Again, there are exceptions, called gynoecious, or all-female cucumbers. Unless there is a male plant nearby, the all-female vines won't produce fruits. And because cross-pollination is involved, pollinating insects such as bees must be present. Or you can do the pollinating yourself with a cotton swab dabbed from a male flower to a female flower.